Today when trying to turn Lumia 920 on I saw a large white sign in the middle of the black screen - a lightning on the left and a gear on the right. The phone was unresponsive. Soft reset fixed it.
Does anybody know what is that supposed to be and what caused it?

Today when trying to turn Lumia 920 on I saw a large white sign in the middle of the black screen - a lightning on the left and a gear on the right. The phone was unresponsive. Soft reset fixed it.
Does anybody know what is that supposed to be and what caused it?